A. O. Smith Water Heater Age by Serial Number

Date-bearing A. O. Smith water heater serial numbers begin with four date digits followed by a unit sequence. Positions 1–2 give the two-digit manufacture year, and positions 3–4 give the production week from 01 through 53.

For example, split serial number 1719106145074 as 17 | 19 | 106145074. The first pair means 2017, the second means production week 19, and the final nine digits identify the individual water heater but do not influence its manufacture date. Appliage uses this structure for dates from 2008 onward. When the full printed serial begins with a valid YYWW code, the serial is enough to return the production week and an estimated age. This format gives a production week rather than an exact month.

Appliage decodes two A. O. Smith date structures. In the modern one, the first two digits are the year and the next two are the production week, so 1719106145074 is week 19 of 2017. That rule applies from 2008 onward, and the year and week tables under A. O. Smith Water Heater Age Rules below list every code it accepts.

Letter-coded serials from 1991 through 2007 also decode. On those older labels a month letter, or a factory letter plus a month letter, comes before a two-digit year, so A00114092 is January 2000. The State water heater age lookup explains the letter tables in full.

A. O. Smith Water Heater Age Rules

A. O. Smith Year Codes (Positions 1–2)

Positions 1–2 are the final two digits of the manufacture year. For example, 08 means 2008, while 17 means 2017.

Appliage supports this year code from 2008 onward. A two-digit value must point to a year from 2008 through the current year.

A. O. Smith Production Week Codes (Positions 3–4)

Positions 3–4 give the production week. The code is the week number itself, so 01 means production week 1 and 19 means production week 19.

Positions 3–4 must contain a value from 01 through 53. A value of 00 or 54 through 99 does not match this A. O. Smith date format.

A production week can cross from one month into another, so this format does not give an exact month. Characters from position 5 onward form the unit sequence. They identify the individual water heater but do not influence its manufacture date. State water heaters can use the same four opening date digits.

In October 2016, A. O. Smith introduced a nine-digit SAP serial. A barcode may contain only that nine-digit number and no date code. On those labels, use the separate BUILD DATE or the four-digit YYWW code printed with the full serial; do not decode the nine-digit SAP number as a date.

A. O. Smith Serial Numbers Appliage Cannot Find the Age

Do not apply the modern rule to older A. O. Smith or State serial-number structures. For example, reading the opening 89 in State serial number 893045678 as a modern year would produce the future year 2089. In A. O. Smith serial number 87C-K-78-44070, a letter interrupts the first four positions, so it does not match the modern four-digit structure. A nine-digit number such as 103475818 is the SAP serial captured by the barcode, not a YYWW date code. Appliage returns no date for these layouts and tells you to look for BUILD DATE on the rating plate.

The decoded week is the manufacture week, not the installation date or warranty start date. Use A. O. Smith’s warranty verification page for coverage records.

Brands That Use the Same Four Digits

State, Reliance, American, and Whirlpool badged tanks all use this layout in Appliage, because A. O. Smith builds every one of them. A federal recall lists these names together and reads prefixes 1115 through 1631 as production weeks from week 15 of 2011 through week 31 of 2016.

American and Whirlpool badged tanks carry the same four date digits further back. American Water Heater Company printed YEAR WEEK beneath the serial on its own labels, and a 2002 federal recall dates serials opening 0124 through 0127 to mid 2001. These records confirm the layout on American labels from 2000 and 2001.

Appliage does not yet include U.S. Craftmaster or Kenmore water heaters. CPSC recall 19-029 lists both names in the same affected serial batches. Rheem water heater age lookup and Bradford White water heater age lookup use different date positions, which are explained in their separate guides.

Sources

• A. O. Smith Service and Warranty Guide. The manual explains the date positions in the A. O. Smith example.
• State Service and Warranty Guide. The State serial example shows where to find the year and week.
• A. O. Smith serial number change notice (2016). The notice says the barcode captures only the nine-digit SAP serial and does not include the date code.
• CPSC: American Water Heater burner recall (02-020). The recalled heaters have serial prefixes 0124–0127 and were sold from June to September 2001.
• American Water Heater label diagram (archived 2003). The pictured labels say YEAR WEEK beneath the serial and show numbers from 2000 and 2001.
• CPSC: A. O. Smith water heater recall (19-029). A. O. Smith and State heaters are both included. The notice explains their year and week prefixes.

For other brands, see our appliance serial number lookup.